XANES Pb LIII spectra of mixed-valence compound: Minium, Pb3O4

TL;DR

This study uses XANES spectroscopy and DFT calculations to investigate the mixed-valence compound Pb3O4, revealing a unified valence state in XANES despite NMR evidence of separate Pb(II) and Pb(IV) ions.

Contribution

The paper provides a combined spectroscopic and computational analysis of Pb3O4, clarifying the apparent contradiction between XANES and NMR results in mixed-valence compounds.

Findings

XANES spectrum indicates an intermediate valence state of Pb.

NMR spectra show distinct Pb(II) and Pb(IV) signals.

The discrepancy is explained by fundamental differences between XANES and NMR.

Abstract

Mixed-valence compound Pb3O4 (minium) has been studied using X-ray absorption near-edge structure (XANES) spectroscopy and DFT calculations. In spite of presence of two valence states of lead [Pb(II) and Pb(IV)], the XANES spectrum of studied system is corresponding to apparently unified, an intermediate valence state of Pb. On the other hand, the 207Pb NMR spectra definitely show two different spectral bands corresponding to different Pb2+ and Pb4+ ions in Pb3O4 crystal structure. The explanation of this contradiction is related to the basics of XANES and NMR spectroscopy.